1. Field of the Invention
The present invention relates to target detecting apparatuses and target detecting processes which can detect various targets such as pathogens, biological substances and toxic substances without using a costly measuring apparatus, which can detect these targets with a low measurement error, high efficiency, simplicity, speed and sensitivity, and which can make a quantitative detection thereof. The present invention also relates to target detection substrates and optical interference substrates which can suitably be used in such apparatuses and processes.
2. Description of the Related Art
In the related art, various kinds of processes have been considered for detecting targets such as pathogens, biological substances and toxic substances, for example, enzyme immunoassay methods such as ELISA. However, in these processes, there was the problem of having to use expensive fluorescent labels or dangerous radiation markers.
Recently, apparatuses and processes have been proposed which detect targets by detecting an interference color change of interference light by a detection layer without using a fluorescence label or a radiation marker. For example, an apparatus has been proposed which measures a thickness change of a nonspecific protein layer as an interference color change using an ellipsometer or the like (e.g., JP-A No. 2002-122603 and JP-A No. 2002-116208). In other proposals, a thickness change is detected as an interference color change in a light reflecting surface by a nucleic acid chain (e.g., Japanese Patent Application Publication (JP-B) No. 07-32720, JP-A No. 10-288616 and JP-A No. 2001-235473). Apparatuses have been proposed wherein light emitted from a light source is irradiated onto a sample surface via a polarizer, the reflected light is reflected by a polarization modulator, and then detected via a polarizer (e.g., JP-A No. 61-34442, JP-A No. 04-78122, JP-B No. 62-57936 and U.S. Pat. No. 4,332,476). Moreover, an apparatus has been proposed which measures a thickness change of a nonspecific protein layer as an interference color change using an ellipsometer or the like, and detects this interference light via a polarizer (e.g., JP-A No. 2002-122603).
However, in these proposals, specific wavelength peaks are measured using an interference filter, a multi-layered structure of optical interference substrates made of silicon nitride, silica, titania, or the like. These proposals therefore have low manufacturing efficiency and high cost. In addition, simple and quick measurement cannot be performed, and there are problems in that the apparatus easily picks up measurement noise, the measurement error is large, measurement sensitivity is poor and a quantitative measurement cannot be made. Thus, there are currently no target detecting apparatuses and target detecting processes which can detect various targets such as pathogens, biological substances and toxic substances without using a costly measuring apparatus, which can detect these targets with a low measurement error, high efficiency, simplicity, speed and sensitivity, and which can make a quantitative detection thereof. Also, there are no target detection substrates and optical interference substrates which can suitably be used in such apparatuses and processes.